JP7279156B2 - Electrostatic chuck and reaction chamber - Google Patents

Description

TECHNICAL FIELD This disclosure relates generally to the field of semiconductor manufacturing, and more particularly to electrostatic chucks and reaction chambers.

In recent years, physical vapor deposition (hereinafter referred to as PVD) technology has been widely used for the formation of aluminum (Al) thin films in the field of semiconductor manufacturing. However, in the process of Al thin film formation, a commonly existing problem is that due to the presence of impurities in the chamber, abnormal growth of the thin film material can occur, resulting in the formation of thorny or angular whisker defects. When the whisker defect size is large enough, product yield can be impacted. Therefore, control of impurity generation during deposition of Al film is an important method and strategy for controlling whisker defect generation.

A high temperature electrostatic chuck is commonly used as the base to support the wafer when the PVD apparatus is used to deposit Al thin films, fix, support or transfer the wafer, and achieve temperature control. Current electrostatic chucks include temperature control devices to control the temperature of the wafer. The temperature control device includes an insulating layer for carrying the wafer, a heating element for providing heat to the insulating layer, and cooling pipes for cooling the heating element.

Existing temperature control devices inevitably have the following problems in practical applications. That is, since the heating element is in direct contact with the cooling pipeline, is the introduction of cooling water into the cooling pipeline possible only during non-process times and not during high-temperature processes? or the water in the cooling pipeline will boil. However, a failure of the cooling pipeline during the process can result in a gradual increase in the temperature of the heating element as the heat generated cannot be effectively discharged in time. As a result, whisker defects increase and product yield is severely affected.

This disclosure is intended to solve at least one technical problem of existing technology. This disclosure provides an electrostatic chuck and reaction chamber that can achieve stable temperature control for the heating body, effectively reduce whisker defects, and improve product yield.

Embodiments of this disclosure provide an electrostatic chuck for achieving the intended purpose of this disclosure. The electrostatic chuck includes a heat insulating layer and a heating element positioned at the bottom of the heat insulating layer. The electrostatic chuck further comprises:
a cooling pipeline configured to convey a cooling liquid, positioned below the heating body and spaced from the heating body;
a thin-walled structure connected with each of said heating body and said cooling pipeline and configured to transfer heat from said heating body to said cooling pipeline;
including.

Optionally, said thin-walled structure comprises a thin-walled heat transfer plate.

Optionally, said thin-walled structure further comprises a ring-shaped connector. The ring-shaped connector is connected to the bottom of the heating element and arranged around the cooling pipeline.
The heat transfer plate is ring-shaped, and the inner and outer walls of the heat transfer plate are in contact with the cooling pipeline and the ring-shaped connector, respectively.

optionally the axial thickness and radial length of said heat transfer plate and/or the contact area where said inner wall and said outer wall of said heat transfer plate contact with said cooling pipe and said ring-shaped connector respectively is set to control the heat dissipation efficiency of the heat transfer plate.

Optionally, the heat dissipation efficiency of said heat transfer plate ranges from 10W to 500W.

Optionally, said heat transfer plate and said cooling pipeline are connected by welding.

Optionally, said thin-walled structure further comprises:
a heat sink in contact with the cooling pipeline and opposite the bottom of the heating body and configured to absorb heat radiated by the heating body in a radiant manner and transfer the heat to the cooling pipeline; assembly,
including.

Optionally, said heat sink assembly includes a heat sink plate fixedly connected to said cooling pipeline. A plurality of heat absorbing sheets are arranged on the surface of the heat absorbing plate so as to face the heating element.

Optionally, said plurality of heat absorbing sheets comprises a plurality of ring structures with different diameters. The plurality of ring structures are arranged concentrically.

Optionally, the cooling pipeline is arranged around the axis of the heat sink plate.

Optionally, the vertical distance between said cooling pipeline and said heating body is in the range from 2mm to 30mm.

Optionally, said vertical distance between said cooling pipeline and said heating body is 5 mm.

As another technical solution, this disclosure further provides a reaction chamber including the electrostatic chuck provided by this disclosure.

This disclosure has the following beneficial effects.

The electrostatic chuck provided by this disclosure can use cooling pipelines and thin-walled structures to provide heat dissipation for the heating element throughout the process. By spacing the cooling pipeline from the heating body, boiling of the coolant introduced into the cooling pipeline during high temperature processes can be avoided. Therefore, the cooling pipeline can be guaranteed for normal use during the process in which whisker defects are effectively reduced. As a result, product yield can be improved.

The reaction chamber provided by this disclosure can achieve stable temperature control for the heating element throughout the process by using the electrostatic chuck provided by this disclosure. This reaction chamber can realize stable temperature control for the heating element and effectively reduce whisker defects during the process. As a result, product yield can be improved.

1 is a schematic structural diagram of an existing electrostatic chuck temperature control device; FIG. 4 is a schematic graph showing the heating element temperature and increasing trend of whisker defects in the existing technology. 1 is a schematic structural diagram of a temperature control device for an electrostatic chuck according to a first embodiment of this disclosure; FIG. FIG. 4 is a schematic structural diagram of a temperature control device for an electrostatic chuck according to a second embodiment of this disclosure; FIG. 4 is a schematic top view of a heat absorbing assembly according to a second embodiment of the disclosure; FIG. 4 is a schematic thermal flow diagram of an electrostatic chuck according to a second embodiment of this disclosure; FIG. 5 is a schematic graph showing the trend of heater temperature and increase in whisker defects according to the second embodiment of the present disclosure; FIG.

For those skilled in the art to better understand the technical solutions of this disclosure, the electrostatic chuck and reaction chamber provided by this disclosure will now be described in detail in conjunction with the accompanying drawings. .

FIG. 1 is a schematic structural diagram of an existing electrostatic chuck temperature control device. As shown in FIG. 1, the temperature control device includes a heating element 1 arranged at the bottom of the thermal insulation layer of the electrostatic chuck and configured to provide heat, and a heating element 1 arranged at the bottom of the heating element 1. , and a cooling pipeline 2 configured to cool the heating body 1 .

When a PVD apparatus is used to carry out the aluminum (Al) thin film deposition process, the process temperature of the Al thin film deposition process is usually 270°C. Target material sputtered from the target during the process can carry high energies. As the target material is deposited onto the wafer, the temperature of the wafer can increase. The heat of the wafer can be transferred through the electrostatic chuck to the heating element 1 at the bottom of the electrostatic chuck, which increases the temperature of the heating element 1 . However, since the heating element 1 is in direct contact with the cooling pipe 2, the introduction of cooling water into the cooling pipe 2 is only possible during non-process times, and the cooling water into the cooling pipe 2 during high temperature processes. Either the introduction of cooling water is not possible or the water in the cooling pipe 2 can boil. However, a failure of the cooling pipe 2 during the process can lead to a gradual increase in the temperature of the heating element 1 because the heat generated cannot be discharged effectively in time. FIG. 2 outlines the temperature rise of the heater and the increasing tendency of whisker defects in the existing technology. As shown in FIG. 2, when the temperature of heating element 1 increases, whisker defects increase, which seriously affects the product yield.

To solve the problems mentioned above, this disclosure provides an electrostatic chuck that includes an insulating layer. The thermal insulation layer can be used to carry the workpiece to be processed. A direct current (DC) electrode may be disposed within the insulating layer and configured to generate an electrostatic attraction between the workpiece and the DC electrode to secure the workpiece to be processed. It is possible. In some embodiments, the _thermal insulation layer is made from a ceramic material (eg, _Al2O3 ).

First Embodiment Referring to FIG. 3, an electrostatic chuck provided by an embodiment of the present disclosure includes a heat insulating layer (not shown) and a heating element 3 positioned at the bottom of the heat insulating layer, and , cooling pipelines 5 and thin-walled structures. The cooling pipeline 5 is arranged below the heating body 3 and is spaced from the heating body 3 . That is, the cooling pipeline 5 and the heating element 3 are completely contactless. The thin-walled structure is connected to the heating body 3 and the cooling pipeline 5 and is configured to dissipate heat from the heating body 3 and transfer heat to the cooling pipeline 5 during the process. During the process, the thin-walled structure can effectively transfer heat from the heating element 3 to the cooling pipes 5 in a timely and efficient manner. In addition, cooling water or other cooling liquid capable of performing a cooling function can be introduced into the cooling pipe 5 to ultimately dissipate the heat from the heating element 3 . Since the cooling pipeline 5 is spaced from the heating body 3, boiling of the cooling liquid introduced into the cooling pipeline 5 during the high temperature process(es) can be avoided. Thus, it can be ensured that the cooling pipeline 5 is used normally throughout the process. As a result, whisker defects can be effectively reduced, improving product yield.

In some embodiments, the cooling pipeline 5 may be placed around the heating element 3 to improve cooling uniformity.

In some embodiments, the thin-walled structure includes a ring-shaped connector 4 and a thin-walled heat transfer plate 6 . A ring-shaped connector 4 is connected to the bottom of the heating element 3 and is arranged around the cooling pipeline 5 .

The heat transfer plate 6 is ring-shaped, and the inner wall and the outer wall of the heat transfer plate 6 are in contact with the cooling pipe 5 and the ring-shaped connector 4, respectively. Heat from the heating element 3 is transferred through the ring-shaped connector 4 to the heat transfer plate 6 and through the heat transfer plate 6 to the cooling pipeline 5 . The heat transfer plates are thin-walled, which means that their axial thickness is much smaller than their radial length.

The thin-walled properties of the heat transfer plate 6 ensure that the heat dissipation efficiency of the heat transfer plate 6 is not too high, even though the heat transfer plate 6 can contact the heating element 3 through the ring-shaped connector 4 . Boiling of the coolant in the cooling pipeline 5 can thus be further avoided. In addition, due to the thin wall characteristic of the heat transfer plate 6, the structure and size of the heat transfer plate 6 can be designed according to the formula of flat plate heat transfer principle so that the heat transfer rate can be precisely controlled. Therefore, stable temperature control for the heating element 3 during the process can be achieved to obtain optimum heat dissipation efficiency.

Specifically, the formula for the flat plate heat transfer principle set forth above is:
Q=λ(T1−T2)tA/δ
where Q denotes the amount of heat per second transferred by the heat transfer plate 6 and has units of J, λ denotes the thermal conductivity of the heat transfer plate 6 and W/(M K ), T1-T2 denotes the temperature difference between the ring-shaped connector 4 and the cooling pipeline 5, and has the unit of K, t denotes the heat transfer time, and A indicates the contact area and has the unit of ^m2 , δ indicates the thickness of the heat transfer plate 6 and has the unit of m.

For example, the temperature T1 at which the heat transfer plate 6 is in contact with the ring-shaped connector 4 is approximately 250° C., and the temperature T2 at which the heat transfer plate 6 is in contact with the cooling pipeline 5 is approximately The temperature is 40° C., the thickness of the heat transfer plate 6 is 0.2 mm, and the contact area is 1.256E-4 m ² . By substituting the above parameters into the equation for the plate heat transfer principle, the amount of heat Q transferred by the heat transfer plate per second is calculated, yielding about 52J. That is, the heat dissipation efficiency of the heat transfer plate 6 under this operating condition is 52W.

Based on the above principle, by changing the size and contact area of the heat transfer plate 6, the heat dissipation efficiency can be controlled within the range of 10W to 500W.

According to the equations of the flat plate heat transfer principle set forth above, the axial thickness and radial length of the heat transfer plate 6 and/or the inner and outer walls of the heat transfer plate 6 are equal to the cooling pipes 5 and By setting the contact area respectively in contact with the ring-shaped connector 4, the heat dissipation efficiency of the heat transfer plate can be controlled.

In some embodiments, the heat transfer plate 6 and the cooling pipeline 5 can be connected by welding. In addition, the heat transfer plate 6 and the ring-shaped connector 4 can also be connected by welding or simply attached to each other.

In some embodiments, a ring-shaped connector 4 can be connected to the bellows to achieve a vacuum seal of the chamber. Specifically, the ring-shaped connector 4 may also include a heat transfer ring. The upper end of the heat transfer ring is connected to the bottom of the heating body 3 and the lower end of the heat transfer ring includes a ring-shaped protrusion. A ring-shaped protrusion protrudes relative to the inner wall of the heat transfer ring and is in contact with the heat transfer plate 6 . In addition, an upper flange is located on top of the bellows and is sealed by and connected with a ring-shaped projection. A lower flange is positioned at the bottom of the bellows and is sealed by and connected with the bottom chamber wall of the reaction chamber. In addition, through holes are provided in the bottom chamber wall. This through hole is located inside the bellows. A lift shaft extends vertically upward through the through-hole from the outside of the chamber to the inside of the chamber. A sleeve is applied to the lift shaft inside the bellows. The upper end of the lift shaft is connected to the upper flange and the lower end of the lift shaft is connected to the drive source. The drive source drives the elevating shaft to drive the electrostatic chuck to move it up and down. Sealing of the chamber can thus be ensured.

In some embodiments, the ring-shaped protrusion of the ring-shaped connector 4 and the upper flange mentioned above can be sealed and connected by welding. The sealing method is applicable to high temperature chambers where high vacuum and granularity are required.

In some embodiments, the distance between cooling pipeline 5 and heating element 3 is in the range of 2 mm to 30 mm, preferably 5 mm. Within that range, boiling of the cooling liquid introduced into the cooling pipeline 5 during high temperature operation can be avoided and the heat from the heating element 3 can be effectively dissipated without delay.

In some embodiments, the heat transfer plate 6 can provide cooling of the heating element 3 through the ring-shaped connector 4, although this disclosure is not so limited. In practical applications, the ring-shaped connector 4 can also be omitted. The heat transfer plate 6 can be connected to the heating body 3 and the cooling pipeline 5 . Therefore, the heat transfer plate 6 can also transfer heat from the heating element 3 to the cooling pipeline 5 . In addition, with the help of the thin-walled properties of the heat transfer plates 6, even when the heat transfer plates 6 are in direct contact with the heating element 3, boiling of the coolant in the cooling pipes 5 cannot occur. Not possible. Cooling of the heating element 3 during the process can thereby be achieved.

It should be noted that in some embodiments the thin-walled structure includes thin-walled heat transfer plates 6 . However, the disclosure is not so limited. In practical application, the thin-walled structure is optional as long as it is possible to achieve heat dissipation of the heating element 3 while ensuring that the coolant in the cooling pipeline 5 does not boil. Other structures may also be included.

Second Embodiment Referring to FIG. 4, an electrostatic chuck provided by an embodiment of this disclosure includes improvements made based on the first embodiment. Specifically, this electrostatic chuck also includes a heat insulating layer, a heating element 3 located at the bottom of the heat insulating layer, a cooling pipeline 5 , a ring-shaped connector 4 and a heat transfer plate 6 . The structure and function of these components are described in detail in the first embodiment, so they will not be described here.

In some embodiments, the electrostatic chuck further includes an endothermic assembly. The endothermic assembly is in contact with the cooling pipeline 5 and is positioned opposite the bottom of the heating element. The endothermic assembly is arranged to absorb the heat radiated by the heating body 3 in a radiative manner and transfer the heat to the cooling pipeline 5 .

With the help of an endothermic assembly, the heat dissipation of the heating body 3, especially in the central area of the heating body 3, can be further increased. Therefore, the heat dissipation rate of the central area can be faster than the heat dissipation rate of the edge area so as to compensate for the temperature difference between the central area and the edge area of the heating element 3 (heat dissipation rate of the central area during the process). temperature rise is more severe). As a result, the temperature uniformity of the heating element 3 can be improved and the temperature uniformity of the workpiece to be treated can be improved.

In some embodiments, the endothermic assembly includes an endothermic plate 7 . The heat-absorbing plate 7 is fixedly connected with the cooling pipeline 5 . In addition, a plurality of heat absorbing sheets 8 are arranged on the surface of the heat absorbing plate 7 and face the heater 3 . Heat from the heating element 4 can be transferred to the heat absorbing sheet 8 through heat radiation and air heat convection, and can be transferred to the cooling pipeline 5 through the heat absorbing plate 7 .

In some embodiments, as shown in FIG. 5, the multiple heat absorbing sheets 8 include multiple ring structures with different inner diameters. The multiple ring structures are concentrically arranged. As a result, the uniformity of cooling of the heating element 3 is improved, and the uniformity of the temperature of the heating element 3 can be further improved.

Of course, in practical applications, the size of the heat-absorbing sheet (including height, thickness, spacing, distribution position, etc.) can be designed according to specific needs.

In some embodiments, a cooling pipeline 5 is arranged around the axis of the heat sink plate 7 to improve heat transfer uniformity.

Additionally, a central hole 71 is located in the heat sink plate 7 and is configured for wiring of DC or heating electrodes to and from the electrostatic chuck.

In the following, a PVD process is taken as an example to describe in detail the heat flow distribution of the electrostatic chuck provided by the embodiments of the present disclosure. Referring to FIG. 6, when the PVD process is performed, the target 9 is plasma irradiated to produce metal ions. Metal ions migrate from the target 9 to the surface of the wafer 11 and carry a certain amount of energy. That energy is converted into heat after the metal ions contact the wafer 11 , which can be transferred to the wafer 11 . It is then possible that the center area of the wafer 11 will gain more energy and the edge area of the wafer 11 will gain less energy. The wafer 11 can transfer its energy to the insulating layer 12 of the electrostatic chuck. The heat insulating layer 12 can transfer the energy to the heating element 3 . Heat from the heating element 3 can be transferred to the cooling pipeline 5 through two paths at the same time and dissipated through the cooling liquid in the cooling pipeline 5 . A first path is a path through which heat can be conducted through the ring-shaped connector 4 to the heat transfer plate 6 and then to the cooling pipes 5 . The second path is the path through which heat can be transferred to the heat-absorbing sheet 8 and heat-absorbing plate 7 through thermal radiation and air thermal convection, and then to the cooling pipeline 5 .

As shown in FIG. 7, the temperature of heating element 3 is maintained essentially constant throughout the process by using an electrostatic chuck provided by embodiments of this disclosure. Thermal equilibrium is achieved. Therefore, whisker defects can be effectively reduced.

As another technical solution, this disclosure also provides a reaction chamber. The reaction chamber includes an electrostatic chuck provided by embodiments of this disclosure.

Specifically, in some embodiments, reaction chamber 10 comprises a PVD chamber, as shown in FIG. A target is placed in the reaction chamber 10 . An electrostatic chuck is placed below the target 9 . The electrostatic chuck includes an insulating layer 12 configured to carry wafer 11 . The insulating layer 12 may be fixed to the heating body 3 by means of pressure rings 13 .

A ring-shaped connector 4 is connected to the bottom of the heating element 3 and arranged around the cooling pipeline 5 . In some embodiments, a ring-shaped connector 4 is connected to a bellows 15 configured to provide a vacuum seal of the chamber. Specifically, the ring-shaped connector 4 may comprise a heat transfer ring. The upper end of the heat transfer ring is connected to the bottom of the heating element 3, and the lower end of the heat transfer ring is arranged with a ring-shaped projection. A ring-shaped protrusion protrudes relative to the inner wall of the heat transfer ring and is in contact with the heat transfer plate 6 . In addition, an upper flange is arranged on top of the bellows 15, sealed by a ring-shaped projection and connected therewith. A lower flange is located at the bottom of the bellows 15 and is sealingly connected to the bottom chamber wall of the reaction chamber or extends outside the reaction chamber 10 and is sealingly connected to a lift shaft (not shown). ing. In addition, through holes are provided in the bottom chamber wall. This through hole is located inside the bellows 15 . A lift shaft extends vertically upward from the outside of the chamber to the inside of the chamber through the through holes. This lifting shaft is sleeved inside the bellows 15 . The upper end of the lifting shaft is connected with the upper flange. A lower end of the lifting shaft is connected to a drive source. The drive source drives the elevating shaft to drive the electrostatic chuck to move it up and down. Sealing of the chamber can thus be ensured.

The reaction chamber provided by this disclosure can achieve stable temperature control of the heater over the course of the process by using the electrostatic chuck provided by this disclosure as described above. Therefore, not only the whisker defects are effectively reduced, but also the optimum temperature efficiency can be obtained.

It should be understood that the above-described implementations are merely exemplary implementations used to illustrate the principles of this disclosure and that this disclosure is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of this disclosure. Those modifications and improvements are also within the scope of this disclosure.

REFERENCE SIGNS LIST 1 heating element 2 cooling pipe, cooling pipeline 3 heating element 4 ring-shaped connector 5 cooling pipe, cooling pipeline 6 heat transfer plate 7 heat absorption plate 8 heat absorption sheet 9 target 10 reaction chamber 11 wafer 12 heat insulation layer 13 pressure ring 15 bellows 71 central hole

Claims (11)

An electrostatic chuck including a heat insulating layer and a heating element positioned at the bottom of the heat insulating layer, further comprising:
a cooling pipeline configured to convey a cooling liquid, positioned below the heating body and spaced from the heating body;
a wall portion connected to each of the heating body and the cooling pipeline and configured to transfer heat from the heating body to the cooling pipeline;
encompasses
wherein the wall portion includes a vertical portion disposed between the heating element and the cooling pipeline, and a thin plate-like heat transfer plate having a ring shape and extending in a radial direction of the ring shape ,
The heat transfer plate has a thickness in the axial direction smaller than the length in the radial direction,
the wall further comprises a ring-shaped connector, wherein the ring-shaped connector is connected to the bottom of the heating body and arranged around the cooling pipeline;
The upper surface of the radially inner end of the heat transfer plate is in contact with the cooling pipeline, and the upper surface of the radially outer end of the heat transfer plate is in contact with the ring-shaped connector . There is an electrostatic chuck. the thickness in the axial direction and the length in the radial direction of the heat transfer plate, and/or the contact area and the outer surface where the upper surface of the inner end of the heat transfer plate contacts the cooling pipeline; 2. A contact area where the upper surface of the side edge contacts the ring -shaped connector is set so as to satisfy the following formula (1) in order to control the heat dissipation efficiency of the heat transfer plate. The electrostatic chuck described in .
Formula (1) Q=λ(T1-T2)tA/δ
where Q denotes the amount of heat transferred per second by the heat transfer plate, λ denotes the thermal conductivity of the heat transfer plate, and T1-T2 denotes the distance between the ring-shaped connector and the cooling pipeline. t is the heat transfer time, A is the contact area between the top surface of the inner end of the heat transfer plate and the cooling pipeline and the outer end of the heat transfer plate indicates the contact area where the upper surface of the contact with the ring-shaped connector, and δ indicates the thickness of the heat transfer plate in the axial direction. 3. The electrostatic chuck of claim 2, wherein the heat transfer plate has a heat dissipation efficiency ranging from 10W to 500W. The electrostatic chuck of claim 1, wherein the heat transfer plate and the cooling pipeline are connected by welding. The wall further includes:
a heat sink in contact with the cooling pipeline and opposite the bottom of the heating body and configured to absorb heat radiated by the heating body in a radiant manner and transfer the heat to the cooling pipeline; 5. The electrostatic chuck of any one of claims 1-4, comprising an assembly. The endothermic assembly comprises:
6. The electrostatic chuck of claim 5, comprising a heat absorbing plate fixedly connected to the cooling pipeline, and a plurality of heat absorbing sheets disposed on the surface of the heat absorbing plate and facing the heating element. 7. The electrostatic chuck of claim 6, wherein the plurality of heat absorbing sheets comprises a plurality of ring-shaped structures with different diameters, and wherein the plurality of ring-shaped structures are concentrically arranged. 7. The electrostatic chuck of claim 6, wherein the cooling pipeline is arranged around the axis of the heat sink plate. The electrostatic chuck of claim 1, wherein the vertical distance between the cooling pipeline and the heating body ranges from 2mm to 30mm. 10. The electrostatic chuck of claim 9, wherein said vertical distance between said cooling pipeline and said heating element is 5 mm. A reaction chamber containing an electrostatic chuck according to any one of claims 1-10.

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